Yeah, like Melee's, but less... original.
I mean like, look at the first section, based on Mario. Have you ever looked at it, objectively?
It's terribly designed and has a lot less to do with Mario than many would like.
Instead, I say just take Level 1-1 from Mario (or the first level of New Super Mario Bros, or Mario World, etc) and add more enemies and a few secrets, and use that. Maybe branching paths, like one way takes you to space (Metroid, Mario Galaxy, F-Zero, Kirby) while another stays on the ground (Sonic, Mega Man, Zelda).
Maybe character specific paths, too. Like, a switch only projectiles can hit, so Marth or Sonic can't go that way.
I dunno, I think it would be cool to have like, Guts Man's stage in 3D or running through Windy Hill Zone with Captain Falcon.